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VFS: Fix automount for negative autofs dentries 

Autofs may set the DCACHE_NEED_AUTOMOUNT flag on negative dentries.  These
need attention from the automounter daemon regardless of the LOOKUP_FOLLOW flag.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Ian Kent <raven@themaw.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
David Howells 2011-07-11 14:20:57 +01:00 committed by Al Viro
parent b4aff1f874
commit 5a30d8a2b8
1 changed files with 15 additions and 9 deletions
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24
fs/namei.c
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@ -716,19 +716,25 @@ static int follow_automount(struct path *path, unsigned flags,
if ((flags & LOOKUP_NO_AUTOMOUNT) && !(flags & LOOKUP_PARENT))
return -EISDIR; /* we actually want to stop here */
/* We want to mount if someone is trying to open/create a file of any
* type under the mountpoint, wants to traverse through the mountpoint
* or wants to open the mounted directory.
*
/*
* We don't want to mount if someone's just doing a stat and they've
* set AT_SYMLINK_NOFOLLOW - unless they're stat'ing a directory and
* appended a '/' to the name.
*/
if (!(flags & LOOKUP_FOLLOW) &&
!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY |
LOOKUP_OPEN | LOOKUP_CREATE)))
return -EISDIR;
if (!(flags & LOOKUP_FOLLOW)) {
/* We do, however, want to mount if someone wants to open or
* create a file of any type under the mountpoint, wants to
* traverse through the mountpoint or wants to open the mounted
* directory.
* Also, autofs may mark negative dentries as being automount
* points. These will need the attentions of the daemon to
* instantiate them before they can be used.
*/
if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY |
LOOKUP_OPEN | LOOKUP_CREATE)) &&
path->dentry->d_inode)
return -EISDIR;
}
current->total_link_count++;
if (current->total_link_count >= 40)
return -ELOOP;